Abstract: The TiAl alloy and 45Cr9Si3 martensitic steel have potential application value in engine valve structures. However, their physical and chemical properties differ significantly, posing substantial obstacles in the welding process. This study demonstrates that resistance welding is a highly efficient method for joining TiAl alloy with 45Cr9Si3 martensitic steel, resulting in a welded junction that is free from any visible fractures, porosity, or other imperfections. A diffusion reaction layer, approximately 5 m thick, is present at the welding interface between TiAl alloy and 45Cr9Si3 martensitic steel. The Fe elements from the 45Cr9Si3 martensitic steel largely diffuse and create a modified diffusion reaction layer on the TiAl alloy side. The weld exhibits a local liquefaction zone, which is formed due to the unequal contact of the welding interface during the initial stages of welding. This uneven contact, along with a high current, causes the contact tip to instantaneously liquefy.